Locking arrangement for electric light bulbs



Oct. 4, 1932; A.. c. T. MYERS 1,881,091

LOCKING ARRANGEMENT FOR ELECTRIC LIGHT BULBS i 1 pairs Patented Oct. 4, 1932 :sr T s PATENT OFFICE nneni nLn cirAnLEs MYERS, or PUR-LEY, ENGLAND, ASSIGNQR To 3'. sToNn 8a COMPANY LIMITED, or nnrrronn, ENGLAND, n conronATIoN or GREAT BRITAIN iooKINe ARRANGEMENT son ELECTRIC LIGHTBULBS Application filediune 25, 1930, Serial No. 1.1%53347, and in Great Britain July 2, 1929.

This invention concerns improvements in and connected with arrangements for locking lamps of the screw-1n plug type 1n their sockets. Usually this provision is directed against lamps locking is particularly c-esirable on theitheft of the'lamp but in the principal application'o'f the present invention the provision of such locking means is alsointended to prevent accidental unscrewing of the lamp due to vibration or similar causes. The particular application referred to is locomotive or like vehicle headlight lamps. WVith such account firstly of the value of the special high powerlamps used and secondly of the danger of the lamps becoming unscrewed owing to the severe vibration to which they are subjected.

The'object of the invention is to provide a simple and reliable locking arrangement the adoption of which will not involve considerable expense nor interfere with the use of the lamps or sockets in the normal fashion. l/Vith these ends in view a locking arrangement according to this invention comprises inaccessible spring catch means arranged to project inside the socket and engage ratchet- V screwing of a lamp into the socket 12, sald like formations in the screw plugs of lamps inserted in said socket. The catch means are arranged to be normally inaccessible and to disengage the same from the socket it is either necessary to disassemble the mounting or securing means from the socket or to destroy the lamp. The former course involves the expenditure of more or less time and trouble which makes theft difficult and snatch-theft impossible. The latter course will be adopted byan authorized person only when the lamp is useless and is of no advantage to a thief for obvious reasons.

One form of locking arrangement for locomotive headlight lamps will now be described by way of example by reference to the accompanying drawing in which Figure 1 is a perspective view of the lamp holder.

Figure 2 is a similar view of a lamp and Figure 3 is a sectional perspective view of the socket to a larger scale.

As may be seen more especially from Figure 3 the threaded socket. 1 is mounted in an insulating body 2 surrounded by a metal shell 3. ,Mounting means 4; are attached to the rear end ofthe insulating body 2. The

socket 1 and the usual spring loaded contact plunger 5 are connected to leads'ti. The locking means shown comprise three spring tongues 7 bent up from the ends and middle of a spring strip 8. Said spring strip is arranged in an annular groove 9 extending around the "exterior of the socket 1, the 1 tongues 7 projecting through holes 10 in the sleeve 1 slightly above a thread thereof. The

plug, portion 11 of the lamp 12 is made with a longitudinal slot or nick 13 one edge 14 of which is depressed below the other to give aratchet tooth efiect. A supporting'guard 15 composed of a plurality of springtongues the tongues of the guard 15' for a purpose to be referred to.

The tongues 7 present no obstacle to the tongues being simply depressed into the groove 9 until they come opposite the slot 13 into which they snap in turn. This does not prevent further screwing in of the lamp,

however, because in the direction of rotation forsu'ch screwing-1n, the tongues encounter a depressed slot edge. On the other hand,

if an attempt is made to unscrew the lamp,

the first tongue 7 to engage the slot 13 enbe locked in any one of a number of posi tions. This enables the spring-loaded contactplunger 5to be depressed to the degree requisite to obtain a proper contact with the centre contactof the plug 11. Alternatively for the same purpose use might be made of a single spring tongue 7 adapted to co-operate 'with two, three or more uniformly spaced slots 13 in the lamp plug 11. It will be seen that the socket 1, makes atight fit with the l'atterh As, moreover, the flange 17 is secured tightly in a recess in the insulating body 2, the catch tongue ortongues 7 are inaccessible unless the plug is destroyed. Themeansfor securing the socket -1 in the insulating body fZ are accessible only at the rear end ofsaid insulating body and are relatively inconvenient tounfasten. In the present instance saidfin'eans' comprise three long "screws 19 (one is shown in Figure 3),

engaging in tapped holes in the flange? on the socket 1 and bearing by means of screw driver-slotted heads on the rear-end surface of the insulating-body 2. The trouble and time involved in dismantling the'mounting will'deter the snatch-theft from removing the lamp.- Naturally it the lamp is broke'noi; defective'th-ere is no essential need to dismantle the mounting to remove said lamp.

{All that-is necessary is to destroy the lamp bulb 1'2fand collapse or deform the plug 11 byipliers Z01" a special pinching tool to disengage, it from the catch, thus permitting removal of the useless plug. 'It will be seen that the, gaps 18 in the guard support c Taoilitat'the gripping ofthe plug ll by .cthepliers or other'tool. V The use of a socket l llmodifie'dfor the purpose of theinvention does not precludejthe use of normal lampsin said socket.

' 1 A locking arrangement for preventing snatch-theft 0f screw-in lamps having ratchet-like,formations in the screw plugs,

which projects from saidsocket.

side of the socket, said strip having at least one tongue bent inwardly to project through a slot inflthe socket and adapted to engage in the ratchet-like' formation in the screw plug;

snatch-theft of screw-in 1 lamps having 4. A locking arrangement for preventing ratchet-like formations 'in the screw-plugs,

comprising a holder, a lamp screw-socket mounted-1n saidholderpsprmg-catoh means accommodated inaccesslbly betweensaid holder and socket and arranged to project Within the socket for engaging in the ratchet like formationsin the lamp plugs screwed into said socket, and'a guard device formembra'cing "the portion of the lamp plug 5. A "locking arrangement as claimed claim 4,1wherein the guard device has longitudinally extending slots permitting of the grippingof the plug of a broken andv defective lamp'bythe jaws of a tool. or c ARCHIBALDYCHARLES TRACEYMYERS.

comprising a. holder, a lamp screw 's'ocket :removably mounted n said holder, sprlngcatch'means accommodated lIlLCCBSSllOlY bethe 'ratchet like formationsTin the lamp plugs screwed into said socket, and a releassnatch-theft of tween said holder and socket and arranged to project within the socket for engaging able connection for securingsaid socket in sald holder, and adapted to release a locked 1amp plug from its socketiby removin g the *sojcket from said holder. I

H2. Ailocking'arrangement for preventing like formations in lamp plugs screwed into,

.:said socket, and 1 long studs extending from the other and remote end of the holder and c entering into the c flange on the socket for -se'curing" the'latter in the holder.

3. A locking arrangement ,as claimed in screw-in lamps" having ratchet-like formations in the screwlu mg'an'extension of the socket for closely claim 1, whereinthe spring catch means ooml prises; an arcuate spring strip accommodated in an annular groove'formed around the out- 

